Drawing devices operating with an upper belt



Aug. 2, 1966 J. PFENNINGSBERG 2,947,033

DRAWING DEVICE OPERATING WITH AN UPPER BELT Filed Nov. 8, 1954 1: i ll I 6' 3 V 9 27 l Inventor fazzrz lingo fie United States Patent 2,947,038 DRAWING DEVICES OPERATINGWITH AN UPPER BELT Josef Pfenningsberg, Munich-Gladbach, Gama as- Signor to Josef Pfenningsberg & Co., Munich-Gladbach, Germany is provided. Individual spring loading has this advantage among others, that it provides the possibility, when Varying the-distance between cylinders, of maintaining the same application pressures.

The known upper belt drafting devices require special careful handling, when it is a question of working up different kinds, quantities and lengths of fibres; For dealing with such a case, it has been proposed to adjust by hand the apron tensioning member together with the pressure-applying roller to a variable distance or a variable position with respect to the lower cylinder. It will be obvious, that in practical operation it will be impossible to be sure of this fine adjustment at the many thousands of spinning places in question.

Through the invention the disadvantages referred to are overcome in a very simple manner. Accordingto the invention there isprovided, -'besides the yielding application pressure provided for each pressure-applying roller, a further yielding application pressure which acts by way 'of a suitable tensioning member on the upper belt.

tion of the upper'belt, more particularlyofthe section coming in contact with the-fibres, will adapt itself auto-a matically to the conditions presented by ;kind, quantity and length of fibre. In the case. of a. short fibrestaple, for instance, the tensioning member willset itself quite automatically into such a position that the roving will be drawn out perfectly satisfactorily; There will be no need for any external intervention. v

The conditions will be specially favourable, when the yielding application pressure acting on the apron tensioning member is resolved into two application pressures acting independently of one another. Oneof the application pressures acts practically perpendicularly to the drafting plane, while the other, smaller application of pressure acts at an angle to the path of the fibres. The first-named perpendicularly 'acting force deals mainly with the quantity of fibre, while the second, lesser force has an equalising effect, when different lengths of fibre are passing, through. According to the invention there act altogether on a single upper belt or apron three yielding forces of different magnitude and different direction, which together influence the drawing operation. This novel system according to the invention operates entirely automatically in so far as it is adapted to deal with different kinds of fibres different quantities of fibres and diiferent lengthsf'of fibres-under the most favourable conditions for the spinning process, without the necessity of any manual adjustments.

Further details of the invention may be gathered from the following description of a constructional example illustrated in the accompanying drawing.

The illustration shows a single upper belt or apron unit with the appertaining pressure-applying arrangements.

With such an arrangement the travel and the posi-l In the constructural example shown are to be seen at 1 the apron tensioning member in the form of a direction-changing rail, at 2 a loading compression spring acting in the direction of the drafting field plane. At 3 is to be seen the second pressure-applying spring, which acts on the tensioning member 1, independently of the first-named spring 2. The recess 4 in the supporting head 5 is under the influence of the loading compression spring 2. 6 is the small belt or apron. 7 is the lower roller and 8 indicates the locus of the variable clamping or the clamping zone, from which the bundle of fibres emerges. A loading compression spring 9 provides pressure for roller 10 against roller 7, the latter being known per se. springs 2 and 9 are housed together with the associated supporting heads 5 and ill and the associated sheathlike parts 12 and 13 in a common casing 14. The sheath-like parts 12 and 13 each form a unit with the supporting head. At .15 and 16 are seen guiding pins for guiding and retaining the supporting heads in the I casing. The guiding pin l6 runs with clearance in the slot 17, while the square pin 15 is guided positively without clearance in the slot 18. This provides, that the supporting head 11 and the associated pressure roller 10 are always held axis parallel with respect to the bottom cylinder 7, while the said pins 15 and :16 also act as holding means, when the system is being unmounted. The mode of support of the supporting head 5 for the apron tensioning member 1, which has a certain amount of clearance, provides, that the apron tensioning member will always set itself with its axis parallel to the bottom cylinder 7. As regards the contact pressure force ratio, the contact pressure force of the spring 9 is the greatest. The contact pressure force 2 is weaker and that of the spring 3 is still weaker. The magnitude of the contact pressure forces should be so selected that, as initially stated, the most favourable drawing out results will be obtained. The member 1 'is convex in cross-section at. the contact surface, While the recess in supporting head 5 is of more or less trapezoidal crosssection. The parts will thus bear in all positions without seizing. l

The sheath-like form of the supporting heads engaging in'the casing has a further special advantage, namely, that the pressure-applying springs are housed in a dustproof manner. This greatly helps to preserve the springs (protection against corrosion and so forth).

The arrangement according to the invention operates as follows:

The fibre roving entering in the direction of the arrow A is gripped between the belt 6 and the bottom roller 7 at B and is carried along to the gripping zone 8 with a yielding, gradually decreasing contact pressure. The decrease in the contact pressure results from the circumstance, that the greatest contact pressure is exerted by spring 9, while weaker contact pressures are transmitted by springs 2 and 3. The fibre roving leaves the system at 8 and is carried along by the next following system in the direction of the arrow C. During the passage of the fibre rovingthrough the system it is found, that some draft takes place along the bearing surface of the belt, with the effect, that the fibres caught by the next following system move forward at the greater speed peculiar to the latter system, whilethe fibres not yet seized by the following system continue to travel along practically at the peripheral speed of the bottom The two load-applying compression apron tensioning member 1 is, as is known, acted upon by only one spring 2, whose direction of pressure runs parallel with the effect of spring 9 for the upper pressure roller 10. From this follows that the loading of the tensioning member 1 consists of two components, of which one runs in the direction of apron 6, while the other acts perpendicularly to the apron. This results in:

(l) a strengthening of the pull in the lower portion of the apron, i.e., an'increase in the contact pressure of the apron against the lower roller;

(2) an increase in the clamping pressure between the apron and the lower roller.

The result of (l) is, on the one hand, a stronger holding effect in general, as well as particularly at the clamping point in connection with (2) between the apron and the lower roller. Thereby especially the longer fibers become involved, and that by means of the strong pull being exerted upon the roving between the indicated clamping point and the draw-off roller. But this causes damage to the fibers and also frequently results in the shortening of many fibers which tear because of this heavy strain. Every pressure increase in the'loading of the tensioning member with only one direction of force therefore endangers the quality of the roving and thereby of the yarn produced on the machine.

It is different in the present invention. The component here present also results in a component in the direction of the lower belt roving and a component perpendicularly to the belt. But the added spring force which acts upon the tensioning member has an effect opposing that component of the spring loading the apron tensioning member which acts in the direction of the belt, so that an added tensioning of the belt does not occur, or at least only to a very minor degree. Thus, the contact pressure of the belt with its disadvantageous results for the quality of the fibers is eliminated in the apparatus according to the invention. Only the increase of the clamping effect between the tensioning member and the lower roller remains. But that has an advantageous effect insofar as short fibers are concerned, as soon as they are released from the clamping point of the rollers of the feed roller pair, they are being braked in their sliding movement through the clamping effect between the tensioning member and the lower roller, and are stretched evenly together with the longer fibers.

The formation of points which affect the quality of yarn unfavorably is thereby avoided with certainty Also a tearing of the long fibers is no longer possible, so that the quality of the roving and therefore of the yarn made from it is improved.

The automatic effect of the new apparatus is explained in that the roving becomes stronger if there is a large number of sho1t fibers present in the roving cross section which can no longer 'be held by the feed roller pair 7, 10, whereby the tensioning member is lifted and that part of the'eifect of the spring 3 which acts in the direction toward the clamping point between the tensioning member and the lower roller is magnified, so that the short fibers are being braked more, so that they cannot be pulled out so rapidly by the draw-E roller pair. The reverse is true if the proportion of short fibers in the roving cross section decreases. In that case, the clamping pressure between the tensioning member and the lower roller is reduced, and the short fibers can follow more easily the pull of the draw-off rollers. In this manner there is obtained a comparative adjustment of the fibers in the roving cross section, which on its part results in an equalizing effect in the roving and of the yarn. Obviously, the system according to the invention adapts itself automatically, owing to the yielding nature of the contact pressure forces, to all occurring conditions. This applies particularly to the different fibrelengths but also to the kind of fibre and the quality of fibre.

What is claimed'is:

1. A single belt drawing device for spinning machinery comprising a lower drafting roller, an upper drafting roller and a belt surrounding said upper roller, belt tensioning means mounted above said lower roller and lying within said belt, independent parallel guides positioned above said lower roller, firstandsecond supporting heads said lower drafting roller to exert radial pressure on said having recesses and mounted on said parallel guides to hold said upper roller and said belt tensioning means respectively in parallelism with said lower roller, resilient means biasing each of said supporting heads downwardly, said belt tensioning means comprising a rail, the upper edge of which seats in a recess in said second supporting head and the lower edge extends angularly downwardly, and a downwardly extending spring mounted on said second supporting head to bear on the lower edge of said rail to bias said lower edge substantially radially toward belt against said lower drafting roller.

2. The single belt drawing device of claim 1 in which the resilient means biasing said belt tensioning means downwardly exerts less force than the resilient means biasing said upper roller.

3. The single belt drawing device of claim 1 in which the guide for said first supporting head carrying the upper drafting roller is so constructed and arranged as to hold said upper roller against any deviation from parallelism the resilient means biasing said belt tensioning means downwardly exerts less force than the resilient means biasing said upper roller, and the spring provided on said supporting head exerts less force than said resilient means biasing said belttensioning means.

5. The single belt drawing device of claim 4 in which said guides are mounted in a dust proof sheath.

. 6. An apparatus for drafting slivers for the production of spun yarn, comprising an upper and a lower drafting roller, a first resilient means for rotatably supporting said upper roller to guide and to press said upper roller toward said lower roller, an endless band around said upper roller of substantially greater circumference than said upper roller, band tightening means in the form of a fiat rail disposed generally tangentially of said lower roller within said band, second resilient means engaging one edge of said flat rail to press said edge in a direction parallel to said first resilient means, and third resilient means to press the other edge of said rail generally radially toward said lower roller.

References Cited in the file of this patent UNITED STATES PATENTS 2,025,394 Langen Dec. 24, 1935 2,209,573 Louie July 30, 1940 2,332,973 Louie Oct. 26, 1943 2,708,290 Neu et al May 17, 1955 2,751,631 Hunter et a1 June 26, 1956 

